Improvement in rolls for pressing, sizing, and calendering paper



UNrrnn STATES PATENT @FFIQE.

FRANCIS CURTIS, OF MALDEN, MASSACHUSETTS.

Specification forming part of Letters Patent No. 51,929, dated January9, 1866.

To all whom "it may concern:

Be it known that I, FRANCIS (loans, of Malden, in the county ofMiddlesex and State of Massachusetts, have invented certain new anduseful Improvements in India Rubber Rolls for the Manufacture of Paperand I hereby declare that the following is a full, clear, and exactdescription of the same.

Inthe manufacture of paper by machinery three principal and importantoperations are effected by means of rolls. When the pulpy mass isdeposited on the wire-cloth it is first carried to a couple of wet-presscylinders, which give the gauze, with the pulp upon it, a slightpressure, which is repeated upon a second pair of wet press-rollssimilar to the first. The web of the paper while yet in a wet state isthen conveyed,by an endless felt, between cast-iron cylinders, which, bysubjecting it to severe pressure, expel the water that remains in theweb, rendering it sufficiently firm to be handled. A second pair ofpress-rollers is generally used to remove the mark of the feltfrom theunder surface of the paper. This operation, which may be simplified ormodified, according to circumstances, is carried out by means ofpress-rolls which, previous to this my invention, were generally made ofcast-iron, the objections to which consisted in their liability tocorrode on the surface, owing to the chemical action of the ingredientsused in the bleaching and other preliminary operations on the pulp.Also, because they are necessarily run wet, the effect of which is thatthe rolls become very rough and sharp, which not only seriously affectsthe surface of the paper, but rapidly Wears out the woolen felting whichpasses with the paper between the surfaces of the iron rolls. 0n theother hand, the corrosion takes place by the formation, upon the surfaceof the rollers, of a pellicle ofiron-rust, which, on coming in contactwith the paper, marks it with iron-rust, rendering it unfit for use.Streaks of such iron-rust are formed by the steel or iron scraper,called doctor, the office of which is to keep the top roll free fromaccumulation of fibrous matter. This action of the doctor loosens therust and deposits it upon the sheet as it passes between the rollers. Toobviate these difficulties in the manufacture of paper, it is true,brass or copper rolls have been used;

but the great expense of such rolls is a bar to its introduction inpaper-mills, and does not compensate for the losses accruing from thecauses before stated.

The object of my invention, therefore, is to protect the surface of ironrolls by coating the same with a substance which is not affected by theacids or alkalies, and which, in point of durability-that is, permanencyof surfaceequals or excels the best copper roll, and which, moreover, iscapable of a high polish or finish; and this I have accomplished, afternumerous experiments and continued tests, by covering the iron with hardrubber or vulcanite. The manner in which the same is or may beconstructed is well known to manufacturers of hard-rubber articles, andno special reference to the manufacture of iron rollers covered withhard rubber is here needed. It may suffice to say that the hard-rubbercompound may be applied in sheets wound around the cylinder or roller,the surface of which is roughened or otherwise made to cause the coatingfirmly to adhere thereto after vulcanization.

Instead of covering an iron roller with rubber, as described, the rollermay be entirely made of rubber, it being wound around a shaft of asquare or other angular sectional area.

Hard-rubber rolls, such as described, of perhaps large diameter, mayalso be used for the finishing operations, such as calendering thepaper. As heretofore made calender-rolls, for calender-in g fine paper,particularl are composed of compressed paper-that is to say, paperpressed by hydraulic pressure onto an iron shaft until the requisitehardness is attained, when they were turned and polished. Theobjectionto these rolls, besides their high cost, is that they areeasily affected by the atmosphere, the dampness rendering them soft,destroying the smoothness of the surface, while if too dry the papershrinks and becomes loose on the shaft. They are also liable to becreased or uneven on their surface. Hard-rubber rolls are entirelyunaffected by the atmosphere and are capable of receiving a far higherpolish,

consequently capable of iuiparting a better, harder, and smoothersurface to the paper as it passes through them, and are much moredurable, not liable to be creased or become uneven, and much more easilykept in repair.

1. As a new manufacture, the employment of hard-rubber rolls inpressing, calendering, and sizing paper.

2. As a new article of manufacture, press,

ealendering, and sizing rollers, to be used in the manufacture of paper,when made of hard. rubber, or of iron or any other material covered withhard rubber.

In testimony whereof I have signed myname to this specification beforetwo subscribing witnesses.

FRANCIS CURTIS.

Witnesses:

FREDERICK CURTIS, C. A. SWADKINS.

